This invention relates to forming of large round bales of crop material, and more particularly to an apparatus and method for monitoring the density of a large round bale during formation.
In forming large round bales of crop material in a baler having a width greater than that of the windrow of crop material, it is important to very the position of the baler relative to the windrow so as to insure uniform bale density and diameter throughout its width. If this is not done, the resulting bale attains an oblong shape, having a lesser density at it ends than at its center. Because of such non-uniform bale density, a bale so formed is difficult to work with and may result in more spoilage than a round bale having a uniform density throughout its width.
A common way to alleviate this problem is for the tractor driver to drive along the windrow in a zig-zag manner in an effort to supply crop material throughout the width of the bale-forming chamber. While this generally improves the shape of the bale, there is a need for a means to monitor the bale as it is being formed, to alert the driver that bale density in one area of the chamber exceeds that in another.
The present invention has as its object to assist the tractor driver in forming a bale having substantially uniform density throughout its width. Another object of the invention is to provide a bale density monitoring apparatus which is simple in design and construction, and which can easily be installed on a baler.
The invention is intended to be used on a baler having a first portion and a second portion defining an internal bale-forming cavity. At least one of the first and second portions is movable to an open position for discharging a formed bale from the cavity. Means is provided for maintaining the movable one of the first and second portions in a closed position during bale formation. The bale monitoring apparatus generally comprises means for sensing pressure exerted on the closing means at a pair of laterally spaced points during bale formation, and indicator means responsive to the sensing means for indicating the presence of a differential in pressure on the closing means at the pair of laterally spaced points. In a preferred embodiment, the movable one of the first and second portions is interconnected with the extendible rod of a hydraulic cylinder provided on each side of the baler, which acts to move the movable one of the first and second portions between its open and closed positions. The means for sensing pressure exerted on the closing means comprises a hydraulic fluid line connected to each one of the pair of hydraulic cylinders. A differential in pressure between the hydraulic cylinders is then sensed by sensing the fluid pressure in the hydraulic fluid lines. A spool member is slidably mounted in a cavity formed in a block and opposite ends of the cavity are exposed to hydraulic fluid pressure in the pair of hydraulic fluid lines. In this manner, when pressure in one of the hydraulic fluid lines exceeds pressure in the other, the spool member is caused to slide toward the end of the cavity having lesser pressure. A pair of activator rods are provided one on either side of the spool member, extending parallel to the direction of sliding movement of the spool member. Each activator rod is disposed within a passage extending from an end of the cavity and opening onto the exterior of the block. Sliding movement off the spool member causes the end of the activator rod to project exteriorly of the block, where it triggers a switch. This provides a signal to the driver to orient the baler on the windrow to supply crop material to the side of the baler having less pressure, so as to equalize pressure in the cylinders. Fluid pressure is preferably communicated from the tractor through the block to the cylinders. The sliding action of the spool member displaces a quantity of hydraulic fluid in the cavity, thereby increasing pressure, and the block preferably includes a pair of pilot operated relief valves arranged one in communication with each end of the cavity for relieving such pressure. The spool member is preferably biased toward a neutral or central position by a pair of springs, provided one on each side of the spool member.
The invention also contemplates a method of monitoring bale formation in a round baler, substantially in accordance with the foregoing summary.